The Fort of São João Baptista de Esposende, also known as Castelo de São João Baptista and Fort of Esposende, is situated in the parish of Esposende, Marinhas and Gandra, within the city and municipality of Esposende in the Braga district of Portugal.

Initially constructed to defend the mouth of the Cávado river, this marine fort was built between 1699 and 1704 during the reign of Pedro II of Portugal (1667-1706). Its original design featured an irregular star-shaped plan with a bulwark at each apex and a hexagonal-shaped guardhouse for each. The fort’s service buildings were situated on its embankment, including an 18th-century chapel.

However, following the installation of a lighthouse, the fort underwent modifications and now has a rectangular plan with only two bulwarks and respective guardhouses at each angle. It comprises four buildings with hipped roofs, some in a state of ruin.

The lighthouse, located on the southwest side of the fort, features a cylindrical iron tower on a circular cement base with a lantern and service balcony painted red. Adjacent to the lighthouse is a rectangular building with two yellow-painted floors designated for the lighthouse keepers.